Acquisition of sensitivity to LH in relation to foetal development stimulation of cyclic AMP and testosterone production in the rat testis

Abstract

The ability of LH to stimulate, in vitro, adenylate cyclase activity and testosterone secretion was studied in foetal rat testes after prelabelling with [ 14C]adenine. As little as 0.1 ng/ml LH produced significant synthesis of cyclic AMP and testosterone secretion. Increase of cyclic AMP production was observed as early as 1 min after addition of LH (100 ng/ml), preceding the rise in testosterone synthesis and secretion. FSH and prolactin were not effective. LH-stimulation of cyclic AMP and testosterone production appeared concomitantly in rat foetal testes on day 15 of gestation and reached a maximum on day 18. Immature testes (14 days) developed functional receptors when cultured in a medium devoid of hormone. The results of the present study suggest that cyclic AMP mediates the effect of LH on steroidogenesis in foetal testes and that the differentiation of functional receptors occurs at the same time as the capacity for testosterone synthesis.